OEGANS OF NUTRITION OR VEGETATION. 



25 



CHAPTER II. 



COMPOUND OEGANS FOEMBD BY THE TISSUES. 



Some plants consist of cells only, -which continue throughout life to 

 produce new cells, and to perform all the vital functions. The great 

 mass of flowering plants, however, although originally cellular, pro- 

 duce organs composed of cells and vessels variously arranged, and " 

 covered by an epidermis. These compound Organs may be divided 

 into Nutritive, or those concerned in the nourishment of the plant ; 

 and Beproduetive, or those which are employed in the production of 

 new individuals. The former consist of the stem, root, and leaves ; 

 the latter, of the flower and fruit. 



Section I. — Organs of NuTeition oe Vegetation. 



1. — Structure, Arrangement, and Special Functions. 



Under this head will be considered the tissues of which the various 

 nutritive organs are composed, the mode in which the parts are 

 arranged, and the particular function which each of the ' organs 

 performs. 



General Integwment. 



Geneeal Integument is the name given to the external cellular 

 covering of plants. It can be 

 easily detached from^young 

 leaves and stems, usually in 

 the form of a colourless trans- 

 parent membrane. By pro- 

 longed maceration it has been 

 shown to consist frequently of 

 ' two layers ; a superficial called 

 Cuticle or Pellicle (fig. 72 pp), 

 and a deep layer, usually called 

 the Epidermis (fig. 72 e e). Dr. 

 Carpenter thinks that the term 

 epidermis should be dropped 

 as regards plants. . He applies 

 the term cuticle to the general 

 integument. 



The Supeeeicial Cuticle ^..^ ^^_ 



or Pellicle {cutis and pellis. 



Pig 72 General integument of a leaf of Iris germanica. VV, The Cuticular pellicle with 

 slits, /, lying upon the proper epidei-mis, e e, formed of hexagonal oeUs, and furnished with 

 stomata, s s. 



